1. Technical Field
The present invention relates to fluid filter assemblies and, more particularly, relates to rolled filter assemblies which have universal applications and which can be removed and installed in a short period of time.
2. Background Art
In a wide variety of fluid processes, it is necessary to remove particles from the fluid by filtration at one or more points in the process. In certain fluid processes, the requirement for various sized filters is dictated by the desired fluid flow rate through the filters, the time intervals or durations between filter changes, the amount of particles in the fluid, and the degree of particle removal that is necessary or desired. In certain processes, where the time interval between filter changes is relatively short, it is important to minimize the amount of liquid that is wasted when the filter is changed, and to minimize the labor and time required to change the filter. In addition, certain processes require that the time required to change a filter be relatively short to minimize interruption of the process.
In many fluid processes, internal bypass of unfiltered fluids is unacceptable. That is, it is extremely important that the filter operate in a manner such that no unfiltered fluid is allowed to bypass the filter medium. In addition to the reliable operation of the filter, it is also desirable to provide a filter that cannot be incorrectly inserted in the filter system in such a manner that such bypass is permitted.
In addition, in many processes involving the use of toxic or hazardous liquids, external leakage of the liquid through assembly error or through failure of the filter is unacceptable.
In many instances, the filters of such processes are self-contained and are directly connected to the liquid conduit of the system. However, filters of this type have a very limited field of use since they are generally compatible with only a single size fluid conduit and only a single connector design. In addition, replacement of such self-contained filters is a relatively time-consuming process and thus may require that the system be shut down for relatively long periods of time while the filter is being replaced. Moreover, the chances of assembly error are relatively high due to the complicated connectors associated with self-contained filters.
Increased flexibility of filtration systems can be provided by designing filter holders integral with the system. Replacement of such filters can be performed relatively quickly by removing the used filter from the holder and by placing a new filter in the holder. However, the flexibility of such devices is limited by the physical dimensions of the filter since typical filter holders are designed to accommodate a filter unit of a single diameter and since these holders have fixed connectors which are suitable for connection to only specific sizes and types of external fluid conduits or piping. Moreover, since the filter units are not self contained, the interior surface of the filter holders is wetted, that is, the filter holder is in direct contact with the fluids. This is undesirable in situations where the fluid is either difficult to clean, incompatible with the materials of the holder, or presents environmental or safety concerns when the filter element is removed from the filter holder after use.
There has thus been a need for the provision of a filter assembly which is flexible, simple, and which can be reliably installed in a relatively short period of time.
There has also been the need for the provision of a filter assembly which includes a self-contained filter which is mounted in a filter holder but which does not wet the filter holder.
There has also been a need for the provision of a filter unit which prevents internal bypass of the fluid being filtered and external leakage of the fluid during filtration but which can be quickly and easily inserted into and removed from a filtration system and which is compatible with a variety of external fluid conduit sizes.
There has also been a need for the provision of a filter unit which is compatible with many different pipe sizes and connector designs and which therefore has universal applications.
There has also been a need for a filter unit which allows for easy change in the filter medium area and dirt handling capacity.
There has also been the need for a filter unit having a filter and holder made of opaque materials so that light sensitive fluids may be filtered in a lighted area.
There has also been the need for a filter unit that allows for use of the system when a filter is not required such as during a cleaning operation.